In-Cylinder Flow Correlations Between Steady Flow Bench and Motored Engine Using Computational Fluid Dynamics

Abstract

Intake port flow performance plays a substantial role in determining the volumetric efficiency and in-cylinder charge motion of a spark-ignited engine. Steady-state flow bench and motored engine flow computational fluid dynamics (CFD) simulations were carried out to bridge these two approaches for the evaluation of port flow and charge motion (such as discharge coefficient, swirl/tumble ratios (SR/TR)). The intake port polar velocity profile and polar physical clearance profile were generated to evaluate the port performance based on local flow velocity and physical clearance in the valve-seat region. The measured data were taken from standard steady-state flow bench tests of an intake port for validation of CFD simulations. It was reconfirmed that the predicted discharge coefficients and swirl/tumble index (SI/TI) of steady flow bench simulations have a good correlation with those of motored engine flow simulations. Polar velocity profile is strongly affected by polar physical clearance profile. The polar velocity inhomogeneity factor (IHF) correlates well with the port discharge coefficient, swirl/tumble index. Useful information can be extracted from local polar physical clearance and velocity, which can help for intake port design.